Method for removing heavy metals and radionuclides from an aqueous solution

ABSTRACT

A solid ion-exchange material useful for removing heavy metals or radionuclides from an aqueous solution comprising a modified clinoptilolite, and methods of using same are provided.

RELATED U.S. APPLICATION

This application is a Continuation-In-Part of patent application Ser.No. 10/271,703, entitled “Method for Removing Heavy Metals andRadionuclides from an Aqueous Solution,” filed Oct. 15, 2002 now U.S.Pat. No. 6,827,859 and is incorporated herein by reference.

FIELD OF INVENTION

The present invention relates to novel solid and liquid ion-exchangematerials useful for removing heavy metals or radionuclides from anaqueous solution and a process for producing the ion exchange materialsthereof. The present invention further relates to a method for removingheavy metals or radionuclides from an aqueous solution using the ionexchange materials of the invention. In one aspect, the inventionrelates to use of solid ion exchange materials, liquid ion exchangematerials, and mixtures thereof useful in said method.

BACKGROUND OF INVENTION

A significant amount of industrial waste water is contaminated withheavy metals such as lead, zinc, copper, antimony, chromium and nickeland radioisotope ions such as radioisotopes of uranium, cobalt, thorium,strontium and cesium. These metals become contaminants in aqueoussystems as the result of activities including chemical manufacture,smelting, electroplating, wood treating, industrial and medical use ofradioisotopes, etc. When such metals are used, metal discharges inaqueous streams severely damage the environment by posing risk to wildlife and human health, and have become a worldwide environmentalconcern. The successful treatment of low level radioactive effluent alsopresents a major challenge to the nuclear industry. Therefore, improvedmethods for removing heavy metals or radioactive isotope ions rapidlyand efficiently from contaminated industrial aqueous solutions arehighly desired.

Existing metal removal methods include standard, conventional techniquessuch as evaporation, precipitation, electrolytic techniques, membraneseparation, fixed and movable bed ion exchange, and activated carbonpurification. However, these methods are not economical or efficientenough in most cases. Zeolites and organically modified smectite clayshave also been used in these applications, but there remains a continualneed to develop improved materials that are more effective for removalof heavy metals and radioisotopes.

Previous studies have identified natural zeolites, e.g. naturallyoccurring clinoptilolite, for use in removing heavy metals andradioisotope ions from aqueous solutions. While natural zeolites havebeen used, they are not sufficiently cost-effective and efficient inremoving heavy metals and radioisotope ions.

It has been suggested to use modified zeolites to improve the metalremoval efficiency of the natural zeolites. U.S. Pat. No. 5,268,107 (the'107 patent) describes a modified clinoptilolite as an ion exchangematerial for the removal of radioisotope cations such as the cations ofcesium (¹³⁷Cs) and strontium (⁹⁰Sr) from an aqueous environmentcontaining radioisotope cations. The modified clinoptilolite of the '107patent is produced by treating a natural clinoptilolite with sodiumhydroxide at a concentration of 0.1 to 5M or with hydrochloric acid at aconcentration of from 0.1 to 5M for a treatment time longer than onehour at a temperature of 30° C. to 80° C. The modified clinoptilolite ispreferably calcined at a suitable calcining temperature of from 400° C.to 500° C. for a calcining time of at least 3 hours. While the modifiedclinoptilolite of the '107 patent is improved over unmodifiedclinoptilolite, it is still desired to have further improvement in theheavy metal or radioisotope ion removal efficiency to have a morecommercially attractive product. Applicants have now discovered animproved modified clinoptilolite based ion exchange materials withimproved heavy metal and radioisotope ion removal efficiency.

SUMMARY OF INVENTION

According to the invention, a solid ion-exchange material useful forremoving heavy metals and/or radionuclides from an aqueous solution isprovided comprising a modified clinoptilolite having a silicon/aluminum(Si/Al) concentration ratio about 1:1 to about 4:1 and a Naconcentration of about 20,000 mg/kg to about 140,000 mg/kg. As usedherein, the Si/Al concentration ratio means the molar ratio of thesilicon atoms versus the aluminum atoms in the solid ion-exchangematerial. A liquid ion-exchange material useful for removing heavymetals and/or radionuclides from an aqueous solution is also providedcomprising: a) about 2,500 mg/L to about 50,000 mg/L Si; b) about 60mg/L to about 1,200 mg/L Al; and c) about 10,000 mg/L to about 200,000mg/L total hydroxide ion.

Further according to the invention, a process for preparing an ionexchange material useful for removing heavy metals or radionuclides froman aqueous solution is provided comprising contacting clinoptilolitewith an alkaline solution at a temperature of about 85° C. to about 300°C. and for a sufficient time to form a treated slurry comprising an ionexchange material having a solid fraction and a liquid fraction. Thesolid ion exchange material is further processed by separating the solidfraction from the treated slurry and washing the solid fraction. Theliquid ion exchange material is further processed by recovering theliquid fraction from the treated slurry. A mixture of the solid ionexchange material and the liquid ion exchange material that can be usedto remove heavy metals or radionuclides from an aqueous solution can bethe treated slurry directly produced, or alternatively, can be preparedby mixing the solid ion exchange material with the liquid ion exchangematerial.

Still further according to the invention, a method for removal of heavymetals or radionuclides from a contaminated aqueous solution is providedcomprising contacting the contaminated aqueous solution with an ionexchange material selected from a solid ion exchange material, a liquidion exchange material, or mixtures thereof, wherein the ion exchangematerial is prepared according to the process of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Not Applicable.

DETAILED DESCRIPTION OF THE INVENTION

As used herein, heavy metals (HMs) are all metals in groups 2 to 16 ofthe periodic table including the lanthanide and actinide series metals(using current IUPAC notation for the periodic table), and thesemi-metallic elements boron, arsenic, selenium, and tellurium. Examplesof HMs include, but are not limited to, lead, zinc, copper, antimony,chromium and nickel. As used herein, radionuclides or radioactivenuclides (Rads) are radioisotopes of all elements. Examples of Radsinclude, radioisotopes of uranium, cobalt, thorium, strontium andcesium.

According to one aspect of the invention, there is provided a solidion-exchange material useful for removing HMs or Rads from an aqueoussolution comprising a modified clinoptilolite having: a) a Si/Alconcentration ratio of about 1:1 to about 4:1; and b) a sodiumconcentration of about 20,000 mg/kg to about 140,000 mg/kg. The solidion-exchange material may also comprise Ca, with concentration of about15000 mg/kg to about 30000 mg/kg. The solid ion-exchange material mayfurther comprise K, with concentration of about 5000 mg/kg to about20000 mg/kg. The solid ion-exchange material may additionally compriseMg, with concentration of about 2500 mg/kg to about 10000 mg/kg; and Ti,with concentration from about 1000 mg/kg to about 3000 mg/kg. The Si/Alratio and metal ion concentrations of the ion exchange material aredetermined using ICP-AES (ICP=Inductively Coupled Plasma and AES=atomicemission spectroscopy). The Si/Al ratio and sodium concentration of theion exchange material are determined using ICP-AES (ICP=InductivelyCoupled Plasma and AES=atomic emission spectroscopy). Preferably, theSi/Al concentration ratio is about 1:1 to about 3:1, and more preferablyabout 1.5:1 to about 3:1. The sodium concentration is preferably about40,000 to about 100,000 mg/kg, and more preferably about 50,000 to about80,000 mg/kg.

Although not to be bound by theory, it is believed that a decrease ofthe Si/Al ratio and an increased sodium content contributes to theimproved performance of the modified clinoptilolite compared to thenaturally occurring clinoptilolite.

There is also provided a liquid ion-exchange material useful forremoving HMs or Rads from an aqueous solution comprising: a) about 2,500mg/L to about 50,000 mg/L Si; b) about 60 mg/L to about 1200 mg/L Al;and c) about 10,000 mg/L to about 200,000 mg/L total hydroxide ion;wherein the Si and Al concentration are determined using ICP-AES. The Siconcentration is preferably to be about 10,000 to about 40,000 mg/L, andmore preferably about 20,000 to about 30,000 mg/L. The Al concentrationis preferably to be about 200 to about 1,000 mg/L, and more preferablyabout 300 to about 700 mg/L. The total hydroxide concentration ispreferably about 50,000 to about 150,000 mg/L, and more preferably about75,000 to about 125,000 mg/L. As used herein, “total hydroxideconcentration” is the concentration of hydroxide present as alkalimetal, alkaline earth metal hydroxide ions, or other alkaline compoundsas employed by the invention. According to another aspect of theinvention, there is provided a method for removing HMs or Rads from anaqueous solution comprising contacting the aqueous solution with an ionexchange material selected from a solid ion exchange material, a liquidion exchange material, or mixtures thereof, wherein the ion exchangematerial is prepared by the process comprising: (a) contactingclinoptilolite with an alkaline solution at a temperature of about 85°C. to about 300° C. and for a sufficient time to form a treated slurrycomprising a solid fraction and a liquid fraction; and optionally, (b)separating the solid fraction from the treated slurry and washing thesolid fraction to produce the solid ion exchange material, and (c)recovering the liquid fraction of the treated slurry from step (b) toproduce the liquid ion exchange material.

According to another aspect of the invention, there is provided aprocess for producing an ion exchange material useful for removing HMsor Rads from an aqueous solution comprising contacting clinoptilolitewith an alkaline solution at a temperature of about 85° C. to about 300°C. and for a sufficient time to form a treated slurry comprising the ionexchange material comprising a solid fraction and a liquid fraction. Thetreated slurry comprising the mixture of the solid fraction and theliquid fraction can be used as the ion exchange material in the methodof the invention for removing heavy metals or radionuclides from theaqueous solution. In the alternative, the solid and liquid fractions canbe recovered to produce the solid ion exchange material and the liquidion exchange material.

In one embodiment of the invention, the ion exchange material is a solidion exchange material that is obtained by separating the solid fractionfrom the treated slurry and washing the solid fraction. The separationof the solid fraction from the treated slurry can be done by anyconventional method known to those skilled in the art. For example, thesolid fraction can be separated using filtration. The recovered solidfraction is then washed or rinsed, preferably with water or a dilutealkaline solution, to produce the solid ion exchange material. Thewashing can be done by any conventional means known to those skilled inthe art. For example, the recovered solid fraction can be rinsed on theseparation apparatus or it can be reslurried and refiltered.

The washing of the solid fraction can be conducted at ambienttemperature or at an elevated temperature. It is currently preferred toconduct the washing at a temperature of about 25° C. to about 100° C.,preferably at a temperature of about 80° C. to about 100° C., with atemperature of about 100° C. being most preferable. The solids can thenbe dried at ambient temperature or dried at an elevated temperature todecrease the drying time. The process of the invention produces a solidion exchange material having substantially increased the ion exchangecapacity compared to an untreated clinoptilolite or a clinoptilolitetreated according to the process of the '107 patent. The solid ionexchange material of the invention is referred to herein as S200.

While not limited thereto, the solid ion exchange material of theinvention does not require a calcining step, i.e. heating at an elevatedtemperature such as >400° C., prior to use in removal of HMs or Radsfrom an aqueous solution.

In another embodiment of the invention, the ion exchange material is aliquid ion exchange material that is obtained by recovering the liquidfraction of the treated slurry, i.e. the mother liquor of the separationstep used to recover the solid fraction. The liquid fraction recoveredis a liquid ion exchange material that is useful for removing heavymetals or radionuclides from an aqueous solution. The liquid ionexchange material of the invention is referred to herein as S200L.

The solid ion exchange material and the liquid ion exchange material canbe used individually in the method of the invention for removing HMs orRads from the aqueous solution. In the alternative, the recovered solidion exchange material and the recovered liquid ion exchange material canbe mixed to form an ion exchange material for use in the method of theinvention for removing heavy metals or radionuclides from the aqueoussolution.

The alkaline compounds in the alkaline solution that can be employed inthe process of the invention are selected from alkali metal hydroxides,alkaline earth metal hydroxides, ammonium hydroxide, tetraalkylammoniumhydroxides, or mixtures thereof.

Examples of suitable alkali metal hydroxides include lithium hydroxide,sodium hydroxide, and potassium hydroxide, with sodium hydroxide andpotassium hydroxide currently being preferred, and sodium hydroxidecurrently being most preferred.

Examples of suitable alkaline earth metal hydroxides include magnesiumhydroxide and calcium hydroxide.

The alkyl groups of the tetraalkylammonium hydroxides can independentlybe the same or different, and are alkyl groups having 1 to about 8carbon atoms, preferably 1 to about 4 carbon atoms. Examples of suitabletetraalkylammonium hydroxides include tetramethylammonium hydroxide,tetrabutylammonium hydroxide, and the like.

The currently preferred alkaline compounds are the alkali metalhydroxides, with sodium hydroxide or potassium hydroxide being morepreferred, and sodium hydroxide being most preferred.

The alkaline solution for use in the invention has a concentration ofabout 0.5M or greater, preferably about 0.5M to about 10M, and morepreferably about 2.5M to about 5M.

The ratio of clinoptilolite to alkaline solution in the slurry willdepend on the particular alkaline compound used and the concentration ofthe alkaline solution. The ratio of clinoptilolite to alkaline solutionin the slurry will be readily apparent to those of ordinary skill in theart without undue experimentation. Typically, the ratio ofclinoptilolite to alkaline solution in the slurry is about 5 to about 50grams clinoptilolite per 100 mL of alkaline solution.

The process of the invention for preparing the ion exchange material canbe conducted at a temperature of about 85° C. to about 300° C.,preferably about 85° C. to about 150° C., and more preferably about 100°C. to about 125° C. The process of the invention for preparing the ionexchange material can be conducted at any suitable pressure based on thetemperature, alkaline compound and alkaline solution concentration used.It is currently preferred to conduct the process for preparing the ionexchange materials of the invention at a pressure of atmospheric toabout 750 psig, with a range of about 20 to about 50 psig being morepreferred. The treatment time in the process of the invention forpreparing the ion exchange material is the time sufficient to preparethe ion exchange material(s) of the invention and will depend on thetemperature, alkaline compound, alkaline solution concentration, andpressure used. Typically, the treatment time is about 0.5 hour to about4 hours, with about 1 hour to about 2 hours being preferred. Processoperating conditions such as treatment time, pressure and temperaturecan be altered by use of an alternative energy source such as microwaveenergy. For example, required treatment time can be substantiallyreduced by operating at higher temperature and pressure.

In a further preferred embodiment of the process of the invention forproducing the ion exchange material (including the solid ion exchangematerial and the liquid ion exchange material), the ion exchangematerial is not produced using added sodium aluminate.

Removal of HMs or Rads from an aqueous solution with the use of solidion exchange material, i.e. S200, can be achieved by contacting thecontaminated aqueous solution with the solid ion exchange material inany conventional method known to those skilled in the art. For example,the contaminated aqueous solution can be passed through a bed or columncontaining the solid ion exchange material. In the alternative, abatchwise method can be used by charging the solid ion exchange materialinto a volume of contaminated aqueous solution, agitating for asufficient period of time, and conducting a liquid/solid separation toremove solids. The contacting time of the solid ion exchange materialwith an aqueous solution containing HMs or Rads is a time sufficient toremove the desired amount of heavy metals or radionuclides from theaqueous solution. The currently preferred contacting time is about 30minutes to about 24 hours. The solid ion exchange material of theinvention can be used with either a basic or acidic contaminated aqueoussolution. The amount of solid ion exchange material to be contacted withthe contaminated aqueous solution will depend on the volume, contaminantlevel, and pH of the contaminated aqueous solution. The amount can bereadily determined by one of ordinary skill in the art without undueexperimentation.

Removal of HMs or Rads with liquid ion exchange material, i.e. S200L,can be achieved by contacting the contaminated aqueous solution with theliquid ion exchange material in any conventional method known to thoseskilled in the art. For example, the liquid ion exchange material can bedirectly contacted with the contaminated aqueous solution in an agitatedvessel. While not wishing to be bound by theory, it is believed that thecontaminants will precipitate from the solution as well asaluminosilicates from the liquid ion exchange material. The contaminantsare believed to be ionically bound to and/or encapsulated with thealuminosilicates present in the liquid ion exchange material andsequestered in the precipitate. A liquid/solid separation is thenconducted to remove the precipitated contaminants from the solution. Theprecipitate is not leachable and non-hazardous by definition ofEnvironmental Protection Agency (EPA) test method 1311, “toxiccharacteristic leach procedure”. The contaminated aqueous solution ispreferably acidic when treatment is conducted with the liquid ionexchange material of the invention. The amount of liquid ion exchangematerial to be contacted with the contaminated aqueous solution willdepend on the volume, contaminant level, and pH of the contaminatedaqueous solution. The amount will be readily determined by one ofordinary skill in the art without undue experimentation.

When the contaminated aqueous solution is contacted with the liquid ionexchange material of the invention and the precipitated contaminantsremoved, the pH of the treated aqueous solution is preferably about 6 toabout 10.

In another embodiment of the invention, the ion exchange material is amixture of S200 and S200L. The mixture of S200 and S200L can be producedby using the treated slurry directly or by mixing the S200 and S200L.Removal of HMs and Rads from an aqueous solution can be achieved bycontacting the mixture with the contaminated aqueous solution for asufficient time so that the metal ions are either bound to the solidS200 or precipitate from the aqueous solution. A liquid/solid separationis then conducted to remove the solids from the solution as describedabove.

In a further preferred embodiment of the method of the invention forremoval of HMs or Rads from a contaminated aqueous solution, the ionexchange material does not contain added sodium aluminate.

The following examples are exemplary of the methods/processes of theinvention.

EXAMPLES Example 1

A slurry comprising 500 mL of 5M NaOH solution and 150 g of a naturallyoccurring clinoptilolite [Zeotech Corporation, from a deposit locatednear Tilden, Tex. were placed in a one liter stainless steel reactor.The reactor was then sealed and the contents brought to a temperature of110° C. This temperature was maintained for 2 hours at a pressure of 25psig. The slurry was agitated throughout the entire treatment. At theend of 2 hours, the slurry was removed from the reactor and filteredresulting into a liquid fraction (S200L) and a solid fraction (S200).The solid fraction was rinsed with 200 mL of 100° C. deionized water.The slurry was again filtered using a vacuum filtration system utilizinga Whatman 542 (2.74 μpore size) filter paper.

Example 2

0.5 g of S200 prepared according to Example 1 was placed in a resincolumn [2.5 cm dia.×20 cm borosilicate resin column manufactured byKontes Glass Company and purchased from Fisher Scientific]. 150 mL of anaqueous solution containing 200 ppm lead was passed through the column.Analysis of the treated solution showed the removal of 99.9% of thelead.

Example 3

A wastewater sample was obtained from a commercial metal finishingplant. Analysis showed the sample to have a zinc concentration of 200ppm. The pH of the solution was 3.6. 100 mL of the solution was placedin a container with 0.5 g of S200 prepared according to Example 1,agitated for 30 minutes and filtered. Analysis of the filtrate showedthe zinc concentration to be 0.15 ppm or that over 99.9% of the zinc hadbeen removed.

Example 4

A 200 mL aqueous solution containing 100 ppm cobalt and 100 ppm antimonywas placed in a container with 1.0 g of S200 prepared according toExample 1 and agitated for 24 hours. Samples were pulled at intervals of30 minutes, 2.5 hours, 12 hours, and 24 hours. Analysis of the samplepulled at the 30-minute interval showed that the cobalt concentrationwas 0.1 ppm and the antimony concentration was 35 ppm, or a 99.9% and65% removal respectively. These concentrations remained consistentthroughout the course of the 24 hour experiment.

Example 5

A wastewater was obtained from a commercial metal finishing plant.Analysis showed the copper concentration to be 1750 ppm and the pH to be1.0. 100 mL of the solution was placed in a container. 15 mL of S200Lprepared according to Example 1 was gradually added to the solution,while stirring constantly. A precipitate formed immediately andcontinued forming throughout the addition of S200L. After the entire 15mL had been added, the pH of the solution had risen to 9. The solutionwas then filtered. Analysis of the filtrate showed the copperconcentration had been reduced to 1.4 ppm, i.e. a 99.9% removal of thecopper.

Example 6

Example 5 was repeated, except a 100 mL aqueous solution with a pH valueof 1 and a lead concentration of 1000 ppm was used. Again 15 mL of S200Lprepared according to Example 1 was added, a precipitate formed and thepH raised to 9. The solution was filtered. Analysis of the filtrateshowed the lead concentration to be 0.1 ppm, meaning nearly all the 100mg of lead in the solution had been sequestered in the precipitate. Theprecipitate was dried for 16 hours at a temperature of 105° C. The drysolid was subjected to a toxic characteristic leach procedure (EPA testmethod #1311). The extraction solution was analyzed showing the leadconcentration to be 0.2 ppm or well under the 5 ppm level needed to bein compliance with EPA guidelines for disposal of solid waste.Therefore, the precipitate is considered to be non-leachable andnon-hazardous.

The solid ion exchange material of the present invention, namely S200,shows tendency to remove HMs and Rads from an aqueous solution morerapidly and efficiently than natural clinoptilolites, other commerciallyavailable ion-exchange materials, and the modified clinoptilolitesdisclosed by the '107 patent. The following examples are exemplary ofthe comparison study.

Example 7

S200 prepared according to Example 1 and a naturally occurringclinoptilolite [Zeotech Corporation, from a deposit located near Tilden,Tex. were tested in duplicate under identical conditions. 0.5 g of eachmaterial was placed in beakers containing 100 mL of a 2000 ppm leadsolution. The aqueous solutions were at a pH of 6.3 and a temperature of25° C. Solutions were agitated for 30 minutes and then filtered. Thefiltrates were analyzed by atomic absorption spectroscopy. The averageresult for the clinoptilolite was a removal of 12.5% of the lead or 25mg. The average result for the S200 was a removal of 80% of the lead or160 mg, showing greater than a 6 fold increase over the naturallyoccurring clinoptilolite in load capacity for lead.

Example 8

S200 prepared according to Example 1, Chabazite (GSA Resource's CabsorbZS500RW chabazite zeolite for the removal of radionuclides), and R&HIRC748 (Rohm & Haas Amberlite IRC748, a resin for the removal of heavymetals) were tested in triplicate under identical conditions. 1.5 g ofeach material (except the sample of IRC 748 which was 3.75 g) was placedin beakers containing 150 mL of a 100 ppm antimony and 100 ppm cobaltaqueous solution. The solutions were at a pH of 6.9 and a temperature of25° C. Samples were taken at 0.5, 2.5, 4, 12, and 24 hours. The averagepercentage for the targeted removal of antimony and cobalt is shownbelow in Table 1 and Table 2, respectively.

TABLE 1 Targeted Antimony Removal (as percent removed) Time [hour] 0 0.52.5 4 12 24 S200 0% 61% 62% 62% 65% 67% Chabazite 0% 20% 26% 28% 48% 51%R & H IRC748 0% 11% 22% 22% 22% 23%

TABLE 2 Targeted Cobalt Removal (as percent removed) Time [hour] 0 0.52.5 4 12 24 S200 0% 100% 100% 99% 100% 98% R & H IRC748 0% 58% 60% 64%85% 89% Chabazite 0% 0% 0% 0% 8% 5%

As can be seen, analysis of the sample pulled at the 30-minute intervalshowed a 61% removal of antimony by S200, a 3-fold greater efficiencythan Chabazite, and about a 6-fold greater efficiency than IRC748. After24 hours, the removal of antimony by S200 was still significantly betterthan for either the Chabazite or the IRC748. In addition, analysis ofthe sample pulled at the 30-minute interval showed a 100% removal ofcobalt by S200, a 1.7-fold greater efficiency than IRC748 and comparedto no removal by Chabazite. After 24 hours, the removal of cobalt byS200 (98% ) was still significantly better than IRC748 whereas removalby Chabazite was still less than 10%.

Example 9

Modified clinoptilolite was prepared according to the conditionsdescribed in the '107 patent. 50 g clinoptilolite was treated in 500 mLof 2M NaOH solution stirred at 50° C. for 8 hours, filtered using aWhatman 542 (2.7 μ pore size) filter paper, then rinsed with deionizedwater, dried and homogenized. 100 mL of an aqueous solution containing100 ppm cobalt was placed in separate containers, one with 0.5 g of S200prepared according to Example 1 and one with 0.5 g of the modifiedclinoptilolite of Example 9, and the samples agitated for 2 hours.Samples were pulled at intervals of 0.5 hour, 1 hour, and 2 hours. Theresults are shown in Table 3.

TABLE 3 Targeted Cobalt Removal (as percent removed) Time [hour] 0 0.51.0 2.0 S200 0% 99.7% 99.7% 99.7% Patent‘107 0% 65.0% 75.0% 85.0%

As can be seen, a removal of 99.7% cobalt by S200 was reached within 30minutes, while a removal of only 85% cobalt was reached by the modifiedclinoptilolites of the '107 patent after two hours. Therefore, S200 ofthe present invention showed an unexpected and significantly higher ionexchange capacity than the product of the '107 patent.

A similar study was conducted using lead instead of cobalt. The materialproduced by replicating the '107 patent process was run in triplicate,as was the S200 material, under identical conditions. 0.5 g of eachmaterial was placed in containers with 100 mL of a solution containing2000 ppm lead and agitated for 2 hours. Samples were pulled at intervalsof 0.5, 1, and 2 hours. Analysis showed the samples were fully loadedafter 0.5 hours as concentrations remained consistent at 1 and 2 hours.The removal of lead is referred to as capacity as the samples wereintentionally overloaded as a means of determining load capacity.

S200 had twice the capacity for removal of lead than the product of the'107 patent (150 mg versus 75 mg). Therefore, S200 of the presentinvention showed an unexpected and significantly higher load capacityfor removing lead than the product of the '107 patent. In addition, theefficiency of lead removal by S200 is greater than 99% up to its loadcapacity.

Example 10

Elementary Study for Solid Ion-Exchange Materials:

A fusion procedure was used to dissolve modified clinoptilolite of theinvention (S200) and unprocessed, naturally occurring clinoptilolite.Samples were run in triplicate. 0.1 g sample of solid ion-exchangematerial (S200) as prepared according to the procedure of Example 1, andnaturally occurring clinoptilolite were each mixed with 0.5 g of lithiummetaborate (from SPEX Certiprep New Jersey, USA) in a weighing boat. Themixture was transferred into a clean graphite crucible and fused in amuffle furnace at 1000° C. for 30 minutes. The crucible was removed andthe molten mass was poured directly into a clean Teflon™ beakercontaining 50 mL of 0.8M nitric acid. The contents of the beaker wereaccurately weighed before and after the addition of the molten sampleand the mixture was transferred to a 125 mL screw-capped polypropylenebottle and made up to 100 ml by the addition of 0.8M nitric acid. Thebottle containing the suspension was placed in a sonic bath until allsolids dissolved, resulting in a clear solution. The samples wereanalyzed using the instrumentation described below and the results aregiven below. As shown by the experimental results, the Si/Alconcentration ratio in the solid ion-exchange material is about 2.7:1,compared to the Si/Al concentration ratio 5.2:1, in the naturalclinoptilolite.

Concentration PPM (mg/kg) Na Mg Al Si P K Ca Ti Mn Fe Ba NaturalClinoptilolite 9083.01 4454.33 53138.6 278420 69.17 12449.7 17203.2958.63 142.38 5484.94 1384.06 S200 65707.8 6073.60 70451.7 193458 103.28760.17 22421.3 1299.64 196.01 8491.84 1594.92

Example 11

Elementary Study for Liquid Ion-Exchange Materials:

The liquid sample (S200L), prepared according to the procedure inExample 1, was analyzed by placing 5 mL of sample into a 100 mL Class Avolumetric flask and made up to 100 mL by the addition of 2.0M nitricacid. Samples were run in triplicate. A procedural blank was alsoprepared and analyzed with samples.

The samples were analyzed using the instrumentation described below andthe results are given below.

Concentration PPM (mg/L) Na Al Si K S200L 95265.3 552.3 24372.1 1848.6

For both solid and liquid sample preparations all acids used werepurchased as the reagent grade and then double distilled usingsub-boiling distillation units.

Instrumentation:

Trace element analysis was conducted using a Plasma Quad model PQ11(Fisons Instruments, Beverly, Mass., USA) inductively coupledplasma-mass spectrometer.

Major element analysis was conducted using ICP-AES, Perkin Elmer modelOptima 3300 XL ICP-OES (OES=Optical Emission Spectroscopy) (Perkin ElmerInstruments, Norwalk Conn., USA). The analysis on samples was carriedout by external calibration and internal standardization procedure.

1. A method for removing heavy metals or radionuclides from an aqueoussolution comprising contacting said aqueous solution with an ionexchange material selected from a liquid ion exchange material, ormixtures of a solid and a liquid ion exchange material, wherein said ionexchange material is prepared by the process comprising: (a) contactingclinoptilolite with an alkaline solution at a temperature of about 85°C. to about 300° C. and for a sufficient time to form a treated slurrycomprising a solid fraction and a liquid fraction, and optionally (b)separating the solid fraction from said treated slurry and washing thesolid fraction to produce said solid ion exchange material; and (c)recovering the liquid fraction of said treated slurry from step (b) toproduce said liquid ion exchange material; wherein said alkalinesolution comprises from about 10,000 mg/L to about 200,000 mg/Lhydroxide ion; and wherein when a solid ion exchange material is used,said solid ion exchange material is the solid ion exchange material ofstep (b); when a liquid ion exchange material is used, said liquid ionexchange material is the liquid ion exchange material of step (c); andwhen a mixture of said solid ion exchange material and said liquid ionexchange material is used, said mixture can be said treated slurryproduced in step (a) or said mixture can be prepared by mixing saidsolid ion exchange material of step (b) with said liquid ion exchangematerial of step (c).
 2. The method of claim 1 wherein said aqueoussolution is acidic.
 3. The method of claim 2 wherein said liquid ionexchange material is contacted with an aqueous solution containing heavymetals and radionuclides for a sufficient period of time to precipitatecontaminants from solution, and conducting a liquid/solid separation toremove the precipitated contaminants from the solution.
 4. The method ofclaim 3 wherein the amount of said liquid ion exchange materialcontacted with said aqueous solution is sufficient to produce an aqueoussolution having a pH after contacting with said liquid ion exchangematerial and removing precipitated contaminants of about 6 to about 9.5. The method of claim 1 wherein said ion exchange material is a mixtureof said solid ion exchange material and said liquid ion exchangematerial.
 6. The method of claim 1 wherein said ion exchange material isa liquid ion exchange material.
 7. A process for producing an ionexchange material useful for removing heavy metals or radionuclides froman aqueous solution comprising: (a) contacting clinoptilolite with analkaline solution at a temperature of about 85° C. to about 300° C. andfor a sufficient time to form a treated slurry comprising said ionexchange material comprising a solid fraction and a liquid fraction; and(b) separating the solid fraction from said treated slurry and washingthe solid fraction to produce a solid ion exchange material; and (c)recovering the liquid fraction of said treated slurry from step (b) toproduce a liquid ion exchange material; wherein said alkaline solutioncomprises from about 10,000 mg/L to about 200,000 mg/L hydroxide ion;and wherein said solid ion exchange material and said liquid ionexchange material is prepared by mixing said solid ion exchange materialof step (b) with said liquid ion exchange material of step (c).
 8. Theprocess of claim 7 wherein said solid ion exchange material of step (b)is dried to produce a dried solid ion exchange material.